Check your switch. I'm going to bet the points are stuck closed. With the building unused, and no water being used, the pump should not even be running, much less running enough to double the electric bill. Even if there was a serious problem with the pump, it would not show up if the pump was not even running.
The switch will be a small grey box with wires attached. See this site for a good view/discussion of it.
How to Find & Adjust the Water Pump Pressure Control - private pump and well system do-it-yourself repairs
Another possibility is a serious leak somewhere or a failed check valve, either of which would cause the pump to cycle many times an hour. You can check those two by simply watching your pressure gauge. When the pump cuts off, the pressure should hold steady.
Still, that shouldn't cause the water to become hot. If the points are stuck, then you will have HIGH pressure. Check your gauge.