There are 2 ways to resolve the issue:

  1. To initiate your Joomla to WordPress migration once again and make use of 301 redirect option – in this way all your Source website links will redirect to the Target ones.
  2. To customize your WordPress permalinks structure so that it fits the Joomla links structure:
  • WordPress Admin -> Settings -> Permalinks.
  • Choose Custom Structure with /%category%/%postname%/.

    More info about permalinks customizing you can find here.