Reloadron's circuit should work, but there is a slight issue with the naming of the switch connections.
I assume that both float switches are identical. To keep the water between the level of the two switches, both switches need to close when the water gets to the float.
Water is below both switches, both are open and the pump stops.
Water is above the lower one, so the lower switch is closed. Pump may be running, or it may not, depending on whether the water was most recently high or low.
Water is above both switches, so both are closed and the pump starts.
So as both switches need to function in the same direction, I would expect them both to be wired to terminals labelled the same on the two switches. In this case, I would expect to wire to COM and N/O, which are likely to be the ones that close when water gets to the float.
N/O stands for "Normally Open", and the term might be a bit confusing in this situation, because the water level will normally be between the two switches, leaving one submerged all the time, so the "normal" condition for that one is to be operated. Reloadron's circuit shows the correct terminals for start and stop pushbuttons, where you don't get someone pressing the button for most of the time, so the start button is normally open and the stop button is normally closed.