BigBen2k,
It is a relatively simply matter to calculate userful work of the pump. It is simply flow rate times pressure rise. Just because this is useful work to us makes no difference. It is still an energy form generated by the electrical input to the motor. Eventually all energy consumed by the pump needs to make its way out and does so as thermal energy.
If someone wishes to calculate the useful pump work, they need a means to measure suction pressure, discharge pressure, and flow rate. Water manometers can do the task, but need to be fairly tall for powerful pumps. I've personally never cared because there isn't a whole lot I can do to change the numbers.
I guess the main point I would make is that all energy consumed by the pump eventually must "leave the box" and does so as thermal energy. Even the portion that generates flow still must leave as thermal energy. Once you turn a pump off, there is some stored energy (both kinetic quickly dissipated and thermal slowly dissipated) that leaves as everything reaches an equilibrium with the ambient conditions.
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