It's essentially a brass/bronze tube right? They should be able to chuck them up on an arbor in a lathe and knurl the outside for part of the length. This will increase the effective diameter and should allow them to be pressed in and hold without any adhesive. May have to play with the depth on one or two to get it right. Might save the cost of custom parts and shouldn't be expensive to do. Should probably be honed internally to correct size because the knurling operation will probably close the hole up a little.