Renaming part of a filename

I have loads of files which look like this:

DET01-ABC-5_50-001.dat
...
DET01-ABC-5_50-0025.dat

and I want them to look like this:

DET01-XYZ-5_50-001.dat
...
DET01-XYZ-5_50-0025.dat

How can I do this?