Pegs
Wooden pegs, little stakes of wood made from maple or lemonwood, usually from Germany. These pegs, in rows of one to three, run from the breast of the heel down the waist of the sole of the boot. Along with stitching and glue, they hold the insole and outsole together. Pegs are usually a sign of a better-quality boot, and you should also be able to see the tops of the pegs when you look inside your boots. Boot maker Ray Jones is the legendary "king of the pegs," known to use as many as 300 pegs per pair.

https://502boots.com/boot-glossary-terms

A pegged sole has wooden pegs made from maple or lemonwood driven through undersized holes, completely piercing the outsole, upper and insole. Then the pegs are floated (smoothed) off on the interior of the boot. These pegs, in rows of one to three deep, run along the arch (shank) of the boot down to the heel. Along with stitching and glue, they hold the insole and outsole together. Pegs are usually a sign of a better-quality boot. If a boot sole is pegged, one can see the tops of the pegs when looking inside the boot.

http://www.hotboots.com/bootinfo/terms.html

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Note added at 21 mins (2016-09-17 17:26:46 GMT)
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Here's a video of the pegging (staking?) process.

https://www.youtube.com/watch?v=n8Vo_DgamX0