Don't make it like a 'punishment', but have him take off the wet bedclothes, carry them to the washer, help you put them in the dryer, and put them back on his bed. Probably won't take many times before he's tired of that and quits wetting the bed. If it doesn't stop the bedwetting, it'll at least teach him that work has to be done all the time by someone, and sometime(s) it'll be by him (and it shouldn't do him any harm. It's simply a 'result' or 'consequence' of a mistake he's made).
Kids are more conscious of what they do in their sleep than we think they are, so if there ARE consequences, they realize what to do (and not do) in their sleep.
When I was 7-9 years old, I slept with my sister (9 years older). She kept telling me that I'd better quit crowding her and 'hogging the covers', so one night she pinched me on the knee. It didn't wake me up (consciously), but I had a nice scratch on my knee the next a.m. and I never crowded her nor pulled the covers afterward (and I still remember the lesson).
Also, I'm 50 and work caring for two mentally and physically handicapped gentlemen who are both 49. One wets the bed almost every night, and we can only say, 'Your bed's wet. Let's change it.' If we say, 'You've peed in the bed', he gets really angry and denies it. He even told me once that it must've rained on his bed. So don't make it about his 'accident'. Make it about taking care of the responsibilities that go along.
Oh, and we've raised 2 girls and 2 boys, and the boys both wet the bed several times after they were 'trained'. (The girls never did!)