If the pump is leaking water at all, this indicates its on its way out ! Water is passing the rubber bearing seals and out through them to the outside world. The bearing wear will accellerate and pretty soon they will collapse. When this happens you may be unfortunate enough to lose the timing of the cams and valvegear as the belt is sometimes common to the water pump and relies on maintaining tension provided by the stability of the pump shaft. Total engine destruction could follow if this happens.
Thats all looking on the 'black side', but really you should get it changed as soon as possible.
Good Luck.
SB
Steve
November 2006