insert, inlay, set, mount, fill, fit into
鑲 centers on fitting one thing tightly into another: inserting, inlaying, setting, mounting, or filling a space so the pieces join securely.
鑲 combines 金 (metal) with 襄, which likely contributes the sound and may relate to assisting or helping, suggesting metal pieces that fit together or assist in joining.
The left side is metal 金, and the right side 襄 looks like a complex object being fitted into place. Picture a metal inlay being carefully inserted into a carved recess.
For ジョウ, imagine a jeweler named Joe who expertly inlays metal into a ring: Joe -> ジョウ, and his work fits perfectly.