2001 Chevy Silverado squeaking from belts?

Have an 01 silverado. Started getting squeaking from the front of the engine. Just like when the belt needs to be changed. Switched the belt several months ago. Squeaking started up again. Father-in-law said I should change out the pulleys. While i'm at it, he said I should change the water pump & tensioner. Ran fine and just started up again. I know some auto repair but, this is driving me nuts. Wondering if you could help me out.