Fuel pump wiring is
external of the tank. The "wet" part of the pump will have o-ring seals that separate input and output, but they also keep fuel from leaking from the pump mount. When a mechanic removes a pump there is a flapper valve that (hopefully) closes when the pump is pulled down from the housing. The three-phase power wires should never come in contact with actual fuel.
This drawing is confusing.....
It makes it seem that the wiring is entering the tank.
I had to look up convoluted (intricately folded, twisted, or coiled) because I've never heard the term before. Basically from what I'm guessing, this is just a protection sheathing running from the elbow at the front spar leading to the pump housing. This travels through a conduit (tube). They want the wires extra protected in this area.
If you look at
this
post..... the 767 uses a white tube with three "supports" (or wings if you would like) separated by 120 degrees. These supports keep the tube centered in the pass-through hole (tube) until the wires are in the pump housing area. You can see from the first picture that the wires in the housing area have clear plastic tubing on them for protection.
I'm assuming the 737 modification that you have is similar in nature. They want the wires protected by this "convoluted" protection while travelling from spar to housing.
I would guess that the sheathing is much smaller in diameter than the elbow and the conduit that it passes through.