Do you have to replace water pump or head if the timing belt goes on a Volkswagen beetle?

In general, no. Like all things mechanical it will depend on several factors. If the engine overheated prior to the timing belt failure then most times the problem is a faulty water pump impeller. Replace the water pump. Until the engine is back running it is difficult to know if there is damage to the head. Check for any signs of water or oil leaks aorund the headgasket. If leakage is present it would be recommended to remove the head for inspection. A broken timing belt can cause other damage such as bent valves which would necessitate head removal and or replacement. (Comments are directed toward the four or five cylinder in-line engines.)