Why do I keep getting '-shm' files on my desktop?

Are these *.db-shm (sqlite3 detritus), or just .shm extensions (such as temporary Audacity work files)? The latter, if from Audacity, should be cleaned up when quitting that application.

Unless you are running WordPerfect in Cross-over for Mac, no version of WordPerfect has been available for Mac since Classic MacOS in the last century.

They are binary files that TextEdit cannot understand. I still believe that these are temporary, sqlite3 shared memory (shm) files which are the by-product of an application that uses the sqlite3 database in macOS. I cannot tell you which application created them though.

https://filext.com/file-extension/SHM

It appears these are Wordperfect documents. LibreOffice may be able to open them if you know the source is legitimate.