steam is coming out of the water pump, but a friend swears its the thermostate ?

Question---is this friend a qualified mechanic? I know they may be trying to save you money , but is the cost of being wrong worth it? Just a thought , NOT trying to 'dis' your friend. IF you put some more conditions of when the 'steam' starts and other things like are you losing coolant and how much? Is it overheating and how often ? Do you have working air conditioning? Is the 'check engine light on? ---Those are all helpful things for us , the more of the story we get , the more accurate our 'guesses' can be.