Wet suites work on principal of after they get wet they don't convect heat. I think certain clothing combination might reach same effect, just not as well.
That's not now wetsuits work. Neoprene is simply a good thermal insulator, largely because of the embedded gas bubbles. And the tight fit minimizes the amount of cold water that can flow into the suit. There is still some heat convection regardless of whether the suit is wet or not.
I can't speak to the physics but I've done cold water dives, and if you prime your wetsuit with a thermos of hot water, that envelope of hot water stays in your suit for a surprising amount of time
