I've justed hemp jersey and sewn it together in lots of layers to make hemp inserts/boosters but it honestly didn't save me very many pennies at all compared with buying hemp inserts from easy-peasy...
Hemp fleece and Hemp jersey are both good for inserts.
Hemp fleece is thicker so for the yardage you'll get more absorbency but it will weigh more so cost you more in postage probably... Inserts will be thicker and stiffer unless you tumble-dry them.
Hemp Jersey is a good insert material and I've only seen hemp jersey used for inserts not hemp fleece.
I think hemp fleece tends to shrink more than the jersey material does too.