What fuel? Petrol and diesel are often pumped from tank to engine using centrifugal or vane type pumps.
What are you trying to actually achieve here, we might be able to help more if you tell us what you're doing.
Normally a fuel pump attached to an engine would be a diaphragm type, or, vane or gear type in most diesels I've worked on.
Fuel pumps inside automotive fuel tanks, which operate submerged in the liquid, frequently have electrical contacts that are completely exposed to the liquid (or vapors, if the fuel level in the tank is low enough)!
Yeah, it's only 12 volts, but 12 volts DC can still make a pretty good spark.
Reason 1: Can't ignite when in a submerged liquid. and the air space above the fuel is either too rich to ignite (gasoline engine) or too lean to ignite (diesel fuel).
Reason 2: It's pretty inaccessible, and not prone to getting a foreign object short-circuiting the terminals.
The problem comes when someone mis-fuels the diesel vehicle with gasoline as they are wont to do from time to time - then it can easily be within the flammable range. KaBoom!
As an illustration of that point, go ahead and try to set a small amount of diesel on fire.
Standard modern vehicle practice is to use a submersible in-tank electric centrifugal pump, with no real effort to waterproof the connections. As long as they're clean and fit well, there's no real concern that sparks or heat might cause a fire. Especially in diesel.
I suggest you spend some time in a wrecking yard to get an idea of what is currently done. If you're still wary of a fire, you can always use an external pump in the fuel line instead.
Standard practice for those of use in the commercial marine world is whatever flavor of pump you like coupled to an off-the-shelf TEFC enclosed motor. Plastic pumps are to be avoided unless they are made from an approved conductive plastic.
While diesel isn't all that ignitable at ambient temperatures, it is non-conductive and that presents a problem from an operator safety standpoint. Pumping non-conductive fluids through non-conductive hoses can create quite the static charge. I have personally seen the lightning bolt run up a person's arm. So make sure you bond your equipment!