That sounds exactly like what I'm experiencing. I'm quite certain that the noise is coming from the water pump but I don't see any leaks. I'll loosen the belt and check the other pulleys including the tensioner, just to be sure. Then I'll tackle the water pump.

How long did it take you to replace the water pump. I know you have to remove the fan, radiator and thermostat housing. Seems like a lot of work. Any tips, shortcut, things to look out for.