Rubbing, whining and grinding noises coming from the water pump are signs the bearings are about to fail. If a water pump is making any kind of noise, it means the pump is likely starting to wear out; a good water pump shouldn't make any sounds at all.
The most common sign of a failing water pump isn't noise but what is called "weeping." Weeping is when small droplets of coolant leak out of the pump and drip onto the exterior surface. Weeping has been deliberately designed into water pumps as a warning sign of imminent failure. If the water pump fails completely, the engine often overheats.