Noun and する verb
そうにゅう
このパラグラフの間にアヤのイラストを挿入するのはどうでしょうか。
Why don’t we insert Aya’s illustration between these paragraphs?
If you insert and enter something, you are doing insertion to it.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.