Well, if we want to get "technical", there is no "sending unit". As per the factory parts book:
11 53020827 1 EK0, EV0 PUMP, Engine Oil
17 04868672AA 1 EK0, EV0 SWITCH, Oil Pressure
I don't know if its a regional thing, as I'm from NJ and we've always generically called anything that sends a signal to a gauge or the computer as a sending unit. I've never heard of a pump itself being called a sending unit. Hopefully the OP got what he needed out of this.
To the OP, these will help:
Factory service manual, click on link, then click on green download button off to right
Factory parts manual