A few things to be aware of when replacing a water pump.
Use an RTV Sealant that is specifically design for Water Pump/Thermostat housing - with Glycol resistance.
This one ->
http://www.permatex.com/products/Aut...one_Gasket.htm
Also
A couple of the lower bolts on the pump will pass through the coolant. Those bolts need to be prepped with sealant as well.
Lastly
Prep and clean your mating surfaces carefully to remove all the old gasket material. When you apply the New gasket sealant use a moderate amount - enough to get the job done - not an overloaded amount.
-The reason for this is excess sealant will find its way into your radiator and clog cooling passages.
Its a straight forward job from there.