Cylinder sleeving is still the most reliable and most economical method of repairing damaged and worn out cylinders, used on older engines.
Damaged and worn cast iron and aluminum engine blocks have long been repaired using dry sleeves. Installing a repair sleeve can often save the block if a cylinder has excessive taper wear, or is cracked, scored or otherwise damaged, and boring out the damaged cylinder.
Likewise, to restore the cylinders to like-new dimensions, all the cylinders in the block can be re-sleeved if all of the cylinders are heavily worn.
The main advantage of sleeving over boring out the cylinders and installing oversized pistons and rings is the cost savings of not having to replace the pistons and rings.
Also, many blocks are too thin to reliably accommodate overboring without sleeves. And if we’re talking an aluminum block with integral iron sleeves, machining out the original sleeves and installing new ones (wet or dry) may be the only way to save (or modify) the block.
See KnowYourParts.com's Installing Cylinder Sleeves to know more.