I know what your describing, and those are a non serviceable part.
They are not sold, or manufactured that i know of.
But don't worry about it. Those things never get replaced anyway, if they survive the removal in the first place.
I have rebuilt, and sold more control arms than i can remember, and those sleves never get reinstalled anyway.
Most control arms that i have come across in my career, never had them in the first place, taking cars apart that never have been apart before.
Jim V.