Doing a cam belt and roller change on my 4A-GE engine and the peg that locates the belt tensioner at the bottom had worked its way out, took a beating from the cam belt which explains why the cam belt had a few mm rubbed off it, then fell off into the muck and debris collected in the bottom of the cover, fortunately it didn't drop into the crank pulley and take the belt off.

I assume they are a press fit

I want to get a new one but don't know the proper name.
What are they called.

It's probably just a metal dowel. I would imagine you can get one from a Toyota dealer. I recently needed a flywheel bolt for my 4age and they got it within 24hrs. They just needed a registration number to put into their parts system to identify the part number. I gave them the registration number of an MR2 that was for sale on Ebay. Job done.

Have a look here, it is not in the camshaft & valve section and is visible but not numbered in the oil pump section.

It does look like the part originally comes as part of the oil pump assembly. You could use an ordinary spring dowel to replace it or get a dowel pin made, it is only used for the tensioner to pivot upon while setting the belt tension. The oil pump location dowels may be the same size , they are p/n 90253-11021 however they may not be a tight enough fit in the pivot dowel hole.

Dave