Transaction is required to perform this operation (either use a transaction or extended persistence context)

I'm using Wildfly 10.0.0 Final, Java EE7, Maven and JPA 2.1. When I am querying my database for records it works fine and lists out the employees, but when I am trying to persist a new employee it gives me the following exception:

javax.servlet.ServletException: WFLYJPA0060: Transaction is required to perform this operation (either use a transaction or extended persistence context)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:671)
io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
...

I'm trying to implement this using JSF and CDI beans. I have a JTA data source, which I've configured in my persistence.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" version="2.1">
    <persistence-unit name="MyPersistenceUnit">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <jta-data-source>java:/EmployeesDS</jta-data-source>
        <class>com.home.entity.Employee</class>
        <properties>
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hbm2ddl.auto" value="update"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
        </properties>
    </persistence-unit>
</persistence>

The CDI bean can be seen below. It is relatively simple, there is a method to list out 25 employees and another which should persist a specific employee:

@Named
@RequestScoped
public class DataFetchBean {
    @PersistenceContext
    EntityManager em;

    public List getEmployees() {
        Query query = em.createNamedQuery("findEmployees");
        query.setMaxResults(25);
        return query.getResultList();
    }

    public String getEmployeeNameById(final int id) {
        addEmployee();

        Query query = em.createNamedQuery("findEmployeeNameById");
        query.setParameter("empno", id);
        Employee employee = (Employee) query.getSingleResult();
        return employee.getFirstName() + " " + employee.getLastName();
    }

    public void addEmployee() {
        em.persist(new Employee(500000, new Date(335077446), "Josh", "Carribean", 'm', new Date(335077446)));
    }
}

The employee entity class can be found below:

@NamedQueries({
        @NamedQuery(
                name = "findEmployees",
                query = "select e from Employee e"
        ),           
        @NamedQuery(
                name = "findEmployeeNameById",
                query = "select e from Employee e where e.empNo = :empno"
        )
})
@Table(name = "employees")
public class Employee {
    @Id
    @Column(name = "emp_no")
    private int empNo;
    @Basic
    @Column(name = "birth_date")
    private Date birthDate;
    @Basic
    @Column(name = "first_name")
    private String firstName;
    @Basic
    @Column(name = "last_name")
    private String lastName;
    @Basic
    @Column(name = "gender")
    private char gender;
    @Basic
    @Column(name = "hire_date")
    private Date hireDate;

    public Employee() { }

    public int getEmpNo() {
        return empNo;
    }

    public void setEmpNo(int empNo) {
        this.empNo = empNo;
    }

    public Date getBirthDate() {
        return birthDate;
    }

    public void setBirthDate(Date birthDate) {
        this.birthDate = birthDate;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public char getGender() {
        return gender;
    }

    public void setGender(char gender) {
        this.gender = gender;
    }

    public Date getHireDate() {
        return hireDate;
    }

    public void setHireDate(Date hireDate) {
        this.hireDate = hireDate;
    }

    public Employee(int empNo, Date birthDate, String firstName, String lastName, char gender, Date hireDate) {
        this.empNo = empNo;
        this.birthDate = birthDate;
        this.firstName = firstName;
        this.lastName = lastName;
        this.gender = gender;
        this.hireDate = hireDate;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Employee employee = (Employee) o;

        if (empNo != employee.empNo) return false;
        if (gender != employee.gender) return false;
        if (birthDate != null ? !birthDate.equals(employee.birthDate) : employee.birthDate != null) return false;
        if (firstName != null ? !firstName.equals(employee.firstName) : employee.firstName != null) return false;
        if (lastName != null ? !lastName.equals(employee.lastName) : employee.lastName != null) return false;
        if (hireDate != null ? !hireDate.equals(employee.hireDate) : employee.hireDate != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = empNo;
        result = 31 * result + (birthDate != null ? birthDate.hashCode() : 0);
        result = 31 * result + (firstName != null ? firstName.hashCode() : 0);
        result = 31 * result + (lastName != null ? lastName.hashCode() : 0);
        result = 31 * result + (int) gender;
        result = 31 * result + (hireDate != null ? hireDate.hashCode() : 0);
        return result;
    }
}

Thanks in advance!