When a t-stat seal leaks, the coolant can drip down and around the bottom of the water pump thus look as though you have a leaking water pump. A new t-stat with seal is about $20 from the dealer and takes minutes to replace.
The only place I see water pumps seap on white engines is from the casting plug ("freeze plug") on its housing, just below the pulley. It usually is just slight seapage leaving a greenish crust but rarely ever really leaking or causing a problem in itself.