For words that have only 3 letters, there isn't a 4th letter. Such as with the word “insert”, there isn't any much more letters Later on and thus need to be the word "incorporate". The word “addict” is during the BIP39 wordlist however you would've utilized “addi” for “addict”. Mnemonic https://thejillist.com/story9886767/bip39-phrase-generator-can-be-fun-for-anyone