The shavings are more likely left over from manufacturing or from a
mischievous person. It would stand to reason that the shavings would
eventually be drawn to the suction end of the pump by vibrations and
currents. And really, you answered your own question when you mentioned
the screen on the pump; how could it be from the pump if it is
screened? Those shavings , if they were to originate from the pump,
they would be found in the fuel filter.
Just get a good magnetic tool and extract the little buggers.