Hello,
Thank you for your question about false results in your page search. This is likely the result of a hack. How this exploit was perpetrated can only be guessed at, but it's possible that the site map was the target.
I recommend upgrading WordPress to the newest version, and making sure that updates are installed immediately as soon as they become available. Cleaning up this hack may require creating a fresh sitemap.
Then, you can submit a reconsideration request to Google. Once Google has made their consideration and re-crawled the site, those results will go away.
Best,
Christopher M.