Spacers should be the same OD as the sealed bearing inner race OD.
If ya use washers as spacers the OD will rub on the sealed bearing shields or OD of the bearing
Bearing, jam nut, lock nut, frame, axle nut? Also depends on which side of the hub we're talking about. The left side will be very different from the cassette right side.
I wonder why his wheel hub came without jam nuts or spacers?
Maybe his wheel hub don't need them and the one nut is enough and is made to be tightened against the bearing inner races.
Like shown in the pic diagram.
Hubs with sealed bearings come with a spacer inside between the two bearings inner races
Or the Axle is designed to support the Sealed bearings inner races.
The bearing nuts are suppose to be tight