Swarf contamination of engine fuel feed lines happened on Airbus A300s 25 years ago. It was picked up in the flight testing stage though. There are a few bits of information missing. I fly the 737 and am assuming that (like Airbus) the design philosophy of Boing fuel systems is essentially the same across the product range.
(1) Did the associated fuel pump low pressure light come on (indicative fuel low pressure filter blockage)?
(2) Did the filter bypass light come on (indicative of high pressure filter bypass).
If the engineers are clear that the contamination came from swarf in the tanks then this rules out fuel pump break up.
In UK engineering speak Swarf normally refers to corkscrew shaped strands of metal (or broken pieces of the same strands...large chips which are measured in milimeters). Swarf comes from drilling operations during manufacture or repair.
If your HP filter was blocked by much smaller chips (dust measured in microns rather than millimeters) this would come from reaming operations of high tolerance assemblys such as the wing/tank undercarridge support structure...or from pump break up. It Should not be referred to as swarf.
The fuel filters on all bowsers are huge (and very expensive). The only way swarf could be introduced from a bowser was if the filters had been removed and not replaced during maintenance. Possible but very very unlikely.
Just to clear up the intended function of aircraft sealant ...it is to seal not as someone said to stop swarf being dragged into the pipes.
That said during manufacture swarf can stick to wet sealant ...much later this swarf can be dislodged and settle at the lowest point in the tank.
Without exteremely dilligent inspection swarf will end up making its way down to the fuel pumps during the early weeks and months of an aircrafts life (or following a major repair).
The only thing I find odd is that your engine failed at low power. Both fuel filters have a bypass (although this is achieved in different ways). The only time you should get fuel cavitaiton is at high altitudes..with high power settings?