When to replace water pump?

[striperman]

Hello all, I have a 50HP 4 stroke 2005..It went into service in april of 2006, I know have about 350 hours on it...I fish alot! Anyway the dealer said replace the water pump impellar every 3 seasons weather or not its needed, with my hours and since this is my second full summer on the motor, should I do it this fall? or do I wait till I have more hours? how long do you guys go? Thanks

[jb123]

i do mine yearly,along with stats , prv and gearcase fliud.