Your plant has scale, a common pest.
OSU has an article here, which ends with this quote: “Scale is more problematic because their clam-shell coverings make it difficult to get to them with any sort of control method. If you catch it early, crush them with your fingers, wash them with soapy water, rinse it and take off the top soil. Once they get established, it’s a more difficult proposition. You can try rubbing alcohol, but you have to reach every insect. During spring when they are in the crawling stage, spray with soap spray. However, many people discard their plant at that point and start over.”