Controlling a 8A DC pump with a PIC
You have drawn a Darlington, not a transistor. Yes, it's feasible (but far from ideal) to use a Darlington, however it will take more current than your PIC can deliver (so another driver would be required) and will get quite warm (stealing power from the pump). A typical part might require 100-200mA of base current and would drop more than 1 volt (2V maximum).  

Instead, I would suggest using a suitable N-channel MOSFET, which can easily handle the current and will run quite cool. You should also put a diode across the pump to deal with motor inductance. You will have more choice in MOSFETs if you add a 12V driver for the gate, which could consist of a few small BJTs and resistors. 

You might be able to get away with a AOI508 with perhaps a 50 ohm series gate resistor directly driven from the PIC. Put a 10K or so to ground so if the PIC GPIO goes high-Z the transistor won't turn partially on and unsolder itself, burn out, etc.