1999 Dodge Dakota Water pump

Have you gotten all three from the same vendor? You may want to try a different vendor, or even a dealer (if that is not where you purchased it). Also does the vehicle have an electric fan or does the fan blade/clutch mount to the water pump pulley? If the blade mounts to the water pump, check for an imbalance in the fan blade itself or the clutch. An imbalance will cause excessive vibration causing the bearings/seals in the w/p to go out.