I would look at it this way.
1) If the float is on, then the pump should be on
2) If the pump is on, there should be a minimum amount water pressure in the outbound line.
So, install a pressure switch on the outbound line. This is pretty easy, you cut out a small section and put a threaded T in which the pressure switch threads to. Connect the pressure switch to the elk.
In addition, put a 120vac relay on the same power cord that goes to the pump itself. When the pump is powered, the relay will close. This is wired in parallel to the pump. Connect the NO contacts on the relay to the Elk
Set your Elk up with a rule
zone pressure switch becomes not secure
and zone power to pump is secure
send some kind of warning
The rule above would trigger every time the water line loses pressure. If the pump is still on when it triggers, you will get warned. This would work to warn you that the pump stopped moving water but is still running. It would not warn you if somehow the pump turned on and never pumped water. In other words, the well was dry, and somehow the pump turned on. This seems highly unlikely, but some rules like this could cover you.
zone power to pump becomes secure
turn output x on for 1 second
output x turns off
and zone pressure switch is not secure
The first rule detects that the pump turned on and triggers a 1 second delay, giving the pump time to start moving the water. The second rule tests the pressure switch after that 1 second delay to ensure the line is pressurized (and thus pump is pumping water).
Finally, you might use 2 pressure switches to warn you in the event of an obstructed outbound line. The second pressure switch would trigger when the pressure exceed some setpoint.
Something like this http://www.amazon.com/Gems-Sensors-Diaphragm-Subminiature-Pressure/dp/B009NAPPGC/ref=sr_1_6?s=industrial&ie=UTF8&qid=1373645428&sr=1-6&keywords=pressure+switch
I do not quite understand the listed range of 20-60 psi. Specifically, I don't know what happens at 60 psi. I assume it is open below 20 psi, closed at 20-60 psi, and now the part that I am unsure of, opens again at 60psi. If indeed it opens again at 60 psi, this single pressure switch would warn you of a running pump that is either under or over pressured (run dry or running against an outflow obstruction).