You need to give more information. First of all, have you been constantly checking the coolant level in the overflow tank, and topping off when necessary? If so, how fast are you losing coolant? You should be able to stay ahead of an overheat by keeping the coolant level topped off. Do you see any sign of wetness on the engine, or anything dripping under the vehicle?

Timing belt breaking normally means bent valves, which in turn means a head gasket replacement. Did all of that happen with yours? Did the T-stat housing or rad leak and cause an overheat? And was that before or after the timing belt broke? It's very unlikely the water pump is your problem right now. It could be a blown head gasket, or (if you're lucky) a simple coolant leak which may be very easy to repair.