I did my own water pump and an intake manifold cleaning at the same time. It's not too bad. I think the key is to use the correct torque and tightening sequence along with new o-rings on the inlet and oil cooler connection point. Not tightening it correctly is probably why so many people get leaks eventually after having a shop do it.
it's not the torque'ing that causes leaks. Shops, including VW dealer techs do not clean the mounting area for the water pump housing. When you mount a new part onto a dirty surface, it will eventually leak.